Gunfire control computer



July 9, 1946.

(Xw) St R. E. CROOKE GUNFIRE CONTROL COMPUTER Filed Feb. 2l, 1941 2Sheets-Sheet 1 ATTORNEY July 9, 1946.y R. E. cRooKE GUNFIRE CONTROL COMPTER its;

Patented July 9, 1946 GUNFIRE CONTROL COMPUTER Raymond E. Crooke, Great Neck, N. Y., assgnor to Ford Instrument Company, Inc., Long Island City, N. Y., a corporation of New York Application February 21, 1941, Serial No. 379,927

8 Claims. (Cl. 235-61.5)

This invention relates to gun-fire control computers and particularly to that type of computers used to control the rng of guns against aircraft.

The problem of the control of gun-fire against aircraft may be divided into two classes; (1) where the aircraft or target is approaching directly towards its objective or the point of observation and the firing gun, and (2) where the target is passing at a distance to one side or the other of the observing and firing point. The invention herein disclosed is applied to the first mentioned class. It will'of course be understood that some of the principles thereof are applicable to the solution of problems of the second mentioned class.

In considering the solution of the problem of anti-aircraft re control to which this invention is applied as one embodiment thereof, it is assumed that the target is directly approaching its objective, which is the point of observation and the point of ring of the gun, at a substantially constant height above the horizontal plane of the objective, such as would be done in horizontal-bombing of a selected point. Upon the picking up of the target by observers at the objective, the slant range of the target and its elevation above the horizontal, expressed in angular units, are observed by instruments well known in the art and from the observed data the height of the target and the horizontal range may be determined, or if the height of the target is known or obtained by observations and the elevation is observed, the slant range and the horizontal range may be determined.

From experimental data obtained during tar# get practices, the most eii'ective ranges of the guns are known as well as the time in seconds required to set and adjust the sights and the fuses of the projectiles and to load and re the projectiles. In this specification, the time required to set the observed values into the mechanisms, for the mechanisms to calculate the advance range or fuse setting and the sight angle, andthe time required to adjust the sight and gun and load and re the gun is defined as the preparation period of time. This preparation period is arbitrarily selected and is based upon experience under various circumstances of operation.

An object of the invention is to provide a mechanism settable in accordance with an observed range or height and elevation angle of an approaching aircraft target and settable in accordance with the speed of the target and the selected preparation period of time following the instant of the observations, for computing the sight angle or diierence in elevation of the gun and the line of sight at the instant of ring and the time-setting values of the fuses of the red projectiles.

It is a further object of the invention to provide a vector analyzer having two concentrically mounted vector arms, the angular position of which represent successive positions of the target. Associated with the vector arms are a component member representing height and two component members representing the horizontal range to successive positions of the target corresponding to the positions represented by the vector arms.

It is a further object to include a timing device to aid in timing the preparation period and in determining or checking the speed of the target or other object.

Mechanisms for accomplishing the objects of the invention and their operation will be understood by considering the following description and accompanying drawings in which:

Fig. 1 is an elevation side view of an aircraft target directly approaching an observing and ring point at a constant height and showing the consecutive angular and linear relations of the target to the observing and iiring point; and

Fig. 2 is a diagrammatic view of a mechanism to compute the values required in the control of the re of the gun.

Referring particularly to Fig. 1, an aircraft or target l is directly approaching the observing and firing point O at a constant height (H) above the horizontal O--O' and at a horizontal speed of St.

When the target I reaches point A, observers at O observe the slant range (R) and the elevation angle of the target (AI), from which the height (H) and the horizontal range (RH) may be calculated by the equations resulting from the right angle triangle OAA of H=R sin A1 and RH=R cos A1, respectively. A is the projection-of the pointV A on the horizontal'O-O;

The preparation period of time (X) is selected as required and multiplied by the speed of the target (St) to give the distance traveled by the target during the time (X) represented by the length of line AB, thus defining the point B at which the target l will be at the end of the preparation period. The value of the distance AB may be expressed by the equation AB=XSt (1) The horizontal range of target I at point B (RHS) is equal to the observed horizontal range minus the distance AB or RH3=RH-X'St (2) From the right angle triangle OBB', the elevation of the target when at point B (A3) will be the angle whose tangent is the height divided by the horizontal range to the point B, or

H .A3-tan 1RH3 (3) From ballistic tables or curves obtained from experimental data the time of flight (t) of the projectiles is known for various combinations of horizontal ranges and heights. As is well known the time of night (t) is the period of time between the instant of firing of the projectile and the instant of its intercepting the target. The travel of the target during this period of time is equal to the speed of the target multiplied by the time of night or t-St, and is indicated on Fig. l by the line BC, or

BC=t-St (4) This distance determines the point of intercept (C) and a perpendicular dropped from C determines the point C. It is obvious that OC' represents the horizontal range to the point of intercept RHz, and that RH2=RH3-(t-St) (5) The elevation angle of the point of intercept (A2) is obtained from the right angle triangle OCC and is the angle whose tangent is the height divided by the horizontal range to the point of intercept (RH2) or .l2=tanR- (6) The elevation of the gun above the line of sight to the point B, to allow for the movement of the target during the time of flight is known as vertical angular deflection (Ut) and may be expressed as Also from ballistic tables and curves obtained from experimental data the correction in elevation, known as super elevation (e), that must be applied to compensate for the shape of the tra- I3 mounted in suitable guides (not shown) to give` jectory of the projectile, is known for various .i0

combinations of horizontal ranges and heights. The total elevation of the gun above the line of sight is known as sight angle (Us) and may be expressed as It is evident that the relation of the elevation angle (As) to the horizontal range RHS and the height (H) may be expressed as Referring particularly to Fig. 2, 2 is a vector analyzer which consists of a disk 3 with a radial range scale 4 engraved thereon and which is rotated about its axis by gear 5 and shaft 6. The radial scale 4 constitutes a vector arm. Shaft 6 is turned by gear `I thereon meshing with gear 8 on shaft 9 on which is secured handle I0. Gear 8 is kept normally in mesh with gear 'I by spring I I bearing on gear 8 and a suitable area on frame l2 of the instrument.

At one side of disk 3 is a first component slide the slide a restrained movement, shown as vertical. Mounted on slide I3 is stiff wire I4 which cooperates with scale I5 to indicate the height represented by the position of slide I3 relative to the center of the disk 3. Slide I3 is moved by shaft I6 geared thereto and on which is secured handle I'l.

Movable in suitable guides and at right angles to slide I3 are a second and a third component slide I8 and I9 on which respectively are mounted stiff wires 20 and 2|. Slide I8 is moved by shaft 22 geared thereto. Shaft 22 is geared to shaft 23 on one end of which is detachable clutch 24 and handle 25 and on the other end of which is slip clutch 26.

Slide I9 is moved by shaft 2l geared thereto at one end. The other end of shaft 21 is connected to one side of differential 28. The other two sides of differential 28 are connected to shaft 22 previously described and shaft 29 the connections for which will be described hereinafter.

Mounted coaxially with disk 3 is a shaft 3D which carries a pointer 3l, constituting a second vector arm. Shaft 3U is geared to one end of shaft 32 on the other end of which shaft is elongated gear 33 which meshes with gear 8 both in the out position of gear 8, as shown in the drawings and in the Lin position, that is, when gear 8 is moved to the right against the force of spring II and out of engagement with gear 1.

Shafts 32 and 6 are connected by differential 34, the output of which is shaft 35. It will be seen that when gear 8 is in mesh with gears I and 33. shafts 6 and 32 are moved simultaneously to rotational positions in accordance with the value of elevation as cranked in by handle I0 but when gear 8 is moved to the in position and handle I0 is turned to move shaft 30 and pointer 3I independently of shaft 6, the output of differential 34, shaft 35, will represent the difference between the rotational positions of shaft 6 and the rotational position of shaft 32.

At the right end of Fig. 2, a stop watch 36 is secured in a casing 3'I which is rotatably mounted on the frame of the computer by support 3B on which support is also mounted reference mark 39. Casing 31 is rotated about its vertical axis by gear 4U which meshes with teeth in rim 4I of casing 3T. Gear 4D is connected to shaft 42 by shaft 43 and gears 44. The rotational position of shaft 42 is set in accordance with the preparation time (X) by handle 45. Casing 31 is so set in relation to shaft 42 that when shaft 42 is in its zero position the zero mark on the face dial ofA watch- 38 is cppositethe Areferencemark 39.7

Watch 36 is started and stopped by a conventional stem 46.

Shaft 42 is connected to a conventional multiplier 4l as one input, the other input, shaft 48, is settable by handle 49 in accordance with the estimated speed of the target (St). The set-in value of St is made visually available by dial 50 geared to shaft 48. The output of multipler 4l, shaft 5I, is connected to slip clutch 26 previously described.

CLJ

Shaft 48 is also connected to a second conventional multiplier 52 the other input of which, shaft 53, is moved in accordance with a computed period of time of fiight of the projectile. The computation or generation of this value Will be described hereinafter. The output of multiplier 52 is shaft 29, previously described.

It is well known in the fire control art that the ballistic factors of time of flight (t) and the super elevation (e) may be determined as functions of the horizontal range and the height of the target. The relation between these factors and the two variables is determined experimentally for each type of gun and projectile and is available in the form of curves or tables. Values of these factors are computed or generated by cam mechanisms indicated generally by the reference numbers 54 and 55, respectively. The details of the two forms of cams do not form parts of this invention, but are included as illustrative of three dimensional cams. The two forms of cams are the subject of a separate application filed on February 1l, 1941, in the name of George Alfred Crowther, Serial No. 377,004.

Cam 54 for generating the value of the time of flight period consists of a plate 56 constrained to move vertically and having two grooves 51 and 58 cut therein forming two cam surfaces. Directly below plate 56 is slide 59, which is moved horizontally by threaded portions of shaft SI) engaging threads in holes near the ends of slide 59. Shaft 6D receives its motion to a rotational position corresponding to the horizontal range of the target (RHZ), by handle 6I. The set-in value of horizontal range (RHZ) is determined by rotating shaft 60 until the zero mark on comparison dial 62 geared to shaft 60 is opposite the zero mark on comparison dial 63 which is geared to shaft 21 previously described.

Directly above plate 55 is a second slide 64, which is moved horizontally by the threaded portion of shaft i6 engaging a threaded hole at the lower end of slide 64. Shaft I6 is moved to positions in accordance with the observed or vectorsolved values of height of the target (H).

Also above plate 56 is output slide 65 which is constrained by guides to move vertically. The vertical motion of slide 65 is transmitted to shaft 53, previously described, by gears 66. A pin 61 sliding in a slot in slide 59 in the groove 51 of plate 56 and in a slot in slide 65 connects these three elements together and a pin 68 in the upper end of slide 64 engages groove 58 in plate 56. It will thus be seen that horizontal movements of slides 59 and 64 will move output Slide 65 vertically as a function of the values of horizontal range (RHZ) and height (H).

Cam mechanism 55 is similar in construction and operation to cam mechanism 54 except that plate 69 is moved about pin 19 by slide 1I which corresponds to slide 64 of cam mechanism 54 thus varying the vertical movement of output slide 12 in accordance with the output value of height (H) as determined by the rotational position of shaft I6. The output of cam mechanism 55, shaft 13, is moved in proportion to the super elevation (e).

The super elevation (e), represented by shaft 13, is combined with the vertical angular deection (A2-A3), represented by shaft 35, in differential 14, the output of which, shaft 15, represents the sight angle (Us) which is made visually available by gearing shaft to dial 16. 'I'his relation is apparent from Equations '1 and 8. Correction to the readings of dial 15 may be made shaft 53 to a graduated dial 8U. Corrections may be added by moving the reference or index line of dial BI, coaxial with dial 80, by shaft 82 turned by handle 83.

It is also well known that the deflection (Ds) of a sight from the bore of the gun to correct for the drift of the projectile is proportional to the angle of super elevation (e). Deflection values for drift are made visually available by gearing output shaft 13 of cam mechanism 55 to a graduated dial 84. Corrections may be added by moving the reference or index line of dial 85, coaxial with dial 84, by shaft 86 turned by handle 81.'

At the outer end of range scale 4 on disk 3 is an arrow 86 which when read against the elevation scale 89 indicates the elevation setting of the disk 3. The angular position of the pointer 3l is also read against this elevation scale.

Operation Before the approach of a target the hand of the stop watch 36 should be set at its zero position by the stem 46 and the Watch as a whole should be turned to its zero position by bringing the zero mark of the dial opposite the reference mark 39 by means of the handle 45. This operation sets the preparation period (X) input to zero.

Upon approach of a target its position is observed in terms of elevation angle (AI) and range (R) or height (H) and the stop watch 36 is started at the instant of making this observation.

The observed value of elevation is set into the mechanism by turning elevation handle I0 in its out position to set the range scale 4 to the observed elevation angle by bringing the arrow 88 to the corresponding graduation of elevation scale 89. This position is indicated by the dotted line 4'.

The height slide I3 and wire I4 are set to the observed value of height (H), as represented by the reading of wire I4 against scale I5, by means of handle I1. If slant range was observed instead of height the wire I4 is brought to intersect the range scale 4 at the graduation representing the observed slant range This sets the height slide and wire to the proper height.

The horizontal range slide I8 and wire 20 are then set by handle 25 in its in position so that the Wire 20 crosses the intersection of the range scale and the height wire as shown by the dotted line 20. While making this setting the clutch 26 slips to permit relative movement between shafts 23 and 5I.

As soon as this setting is made the handle 25 is returned to its out position and the slide I3Y c' t' and wire 20 are free to be moved by the multiplier 41 the inputs of which are now set to the observed value of target speed (St) by means of the handle 49 and dial 50, and the desired value of preparation period (X) by means of the handle 45 which also bodily turns the stop watch 36 vuntil its dial read against the reference mark 39 indicates -the preparation period.

The movement or position o-,the output shaft 5I -of multiplier 41 now represents X-St or the 7 distance AB of Fig. 1. Because the handle 25 is now in its out position shaft 5I 'drives shaft 23 through the clutch 26 and slide I8 with wire 2D are moved to the left an amount representing AB or X -St so they now represent the horizontal range (RHS) as will be evident from Equation 2.

If the target speed is not accurately known from observation it may be obtained by using the apparatus in the following manner. After setting the vector analyzer in accordance with the first observed position of the target, a second set of observations of the position of the target is made at a known time interval (Xs) after the rst observation. This time interval can be conveniently determined from the stop watch 36, which was started when the first observation was made, by turning the case of the watch by the handle 45 to keep the hand of the watch opposite the reference mark 39 until the second observation is made. The turningpofe-the case is stopped at this instant and the dial reading opposite the mark 39 will indicate the time interval which interval has been set into the multiplier 41. If the target speed (St) was correctly set the horizontal range wire 20 will cross the intersection of the height wire I4 and the range scale 4 when the disk 4 is turned to the new observed elevation (AS) and will act as an index of the computed position of the target. 1f the range wire 20 does not cross the intersection the target speed (St) setting should be changed until it does. The target speed setting will then be correct. Having thus checked or determined the target speed the handle 45 is turned to introduce the full preparation period (X) to turn the watch case and to introduce the preparation period into the multiplier 41. From this point on the operation is as otherwise described.

With the handle I still in the out position the disk 3 is rotated so the range scale 4 crosses the new intersection of the horizontal range wire 20 and the height wire I4. Froml Equation 3 it will be seen that the angle of the disk 3 now represents the elevation angle (A3) which may be read from the indication of arrow 88 on the elevation scale 89. This condition is shown in solid lines on Fig. 2.

While the above settings are being made the comparison dial E2 is kept matched with the dial 63 by means of the handle 6 I. This operation sets the horizontal range (RHZ) into the cam mechanism 54 which together with the height setting introduced by the handle I1 gives an output of time of flight which is introduced into the multiplier 52 by shaft 53. The movement or position of the output shaft 29 of this multiplier represents t-St or the distance BC of Fig. 1.

The movement of shaft 29 is combined by differential 28 with the position of shaft 22, which has been set to represent horizontal range (RI-I3), so that the movement or position of shaft 21 and dial 83 represent horizontal range (BH2) as may be seen from Equation 5.

dItmvill be observed thatgas shaft 60 and dial 62 are turned to match dial 63 that the position of dial 83 is modified because of the connection of shaft 6D through the cam mechanism 54, shaft 53, multiplier 52, shaft 29, differential 28 and shaft 21. It will be evident however that since the direct effect of movement of handle I on dial 62 is much greater than the indirect effect of such movement on dial 63 that no difficulty is experienced in bringing the dials to a matched condition.

Since shaft 21 now represents horizontal range (BH2) the slide I9 and wire 2l will be positioned to represent this value. The handle I0 is now shifted to its in position and pointer 3| is turned to cross the intersection of the horizontal range (RHZ) wire 2I and the height (H) wire I4. It will be seen from Equation 6 that the position of pointer 3| now represents the elevation angle (A2) which may be read from scale 89. The values of A2, represented by the rotation of shaft 32, and of A3, represented by the rotation of shaft 6, are combined by differential 34, the rotational position of the output of which, shaft 35, represents the vertical angular deflection (Ut) as will be seen from Equation 7.

Shaft 63 also sets in the value of horizontal range (RH2) into cam mechanism 55, the output of which, shaft 13, is moved in proportion to the super elevation (e) The movement of shafts 35 and 13 are combined by differential 14 to obtain the sight angle (Us) which .is used for adjusting the relative vertical angle between the sight and the gun, This angle is represented by the rotational position of shaft 15, which is geared to dial 16.

The values of the fuse settings and the deflection are available as previously described.

The sight and fuse setting data thus obtained are correct for firing the gun at the end of the preparation period, as indicated when the hand of Watch 36 comes opposite reference mark 39.

It is obvious that various changes may be made by those skilled in the art in the details of the invention as disclosed in the drawingsl and described above within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. Apparatus for use in aiming a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer including two independent rotatable vector arms and means to angularly adjust the positions of the arms and including a rst component slide and means to move the said slide to positions in accordance with the height of the target and second and third component slides and means to simultaneously set the second and third slides in accordance with values of horizontal range and to independently set the third slide relative to the second slide in accordance with changes in values of horizontal range, means settable in accordance with a selected preparation period of time, means settable in accordance with the estimated speed of the target, a first multiplier the inputs of which are connected to the preparation period setting means and the target speed setting means and the output of which is connected to the second and third simultaneous slide setting means, a second multiplier with inputs settable in accordance with the speed of the target and a computed flight period and having an output connected to the third slide independent setting means, ballistic computing means forAcomputing the flight period and settable in accordance with the position of the first slide and in accordance with the p0- sition of the third slide including an output moved in proportion to the computed ight period, motion transmitting means connecting the output of the computing means to the flight period input of the second multiplier, means to set the vector arms in accordance with the elevation angle of the target at selected positions, a differential the inputs of which are moved in accordance with the positions of the two vector arms and the output of which is responsive to the difference in movement of the two vector arms, a second ballistic computing means for computing super elevation angles and settable in accordance with the position of the rst slide and in accordance with the position of the third component slide including an output moved in proportion to the computed super elevation angle, and a second differential connected to the output of the first differential and the second ballistic computing means, whereby the output of the second differential is moved in proportion to the sight angle.

2. Apparatus for use in aiming a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer including a iirst component slide and means to move the said silde to positions in accordance with the height of the target and second and third component slides and means to simultaneously set the second and third slides in accordance with values of horizontal range and to independently set the third slide relative to the second slide in accordance with changes in values of horizontal range, means settable in accordance with a selected preparation period of time, means settable in accordance with the estimated speed of the target, a first multiplier the inputs of which are connected to the preparation period setting means and the target speed setting means and the output of which is connected to the second and third simultaneous slide setting means, a second multiplier with inputs settable in accordance with the speed of the target and a computed ight period and having an output connected to the third slide independent setting means, ballistic computing means for computing the flight period and settable in accordance with the position of the first slide and in accordance with the position of the third slide and including an output moved in proportion to the computed iiight period, motion transmitting means connecting the output of the computing means to the iiight period input of the second multiplier, a timing device settable by the preparation period setting means, and means juxtaposed the timing device for indicating the terminaticn of the preparation period.

3. Apparatus for use in aiming a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer including a iirst component slide and means to move the said slide to positions in accordance with the height of the target and second and third component slides and means to simultaneously set the second and third slides in accordance with values of horizontal range and to independently set the third slide -relative t the second slide in accordance with changes in values of horizontal range, means settable in accordance with aselected preparation period of time. means settable in accordance with the estimated speed of the target, a rst multiplier the Vinputs of which are connected to the preparation period setting means and the target speed setting means and the output of which is connected to the second and third simultaneous slide setting means, a second multiplier with inputs settable in accordance with the speed of the target and a computed flight period and having an output connected to the third slide independent setting means, ballistic computing means for computing the flight period and settable in accordance with the position of the iirst slide and in accordance with the position of the third slide including an output moved in proportion to the computed night period, motion transmitting means connecting the output of the computing means to the night period input of the second multiplier, a watch settable about an axis perpendicular to the center of its face by the preparation period setting means, and a reference mark juxtaposed the face and the hand of the watch for indicating the termination of the preparation period,

4. Apparatus for use in aiming a gun for ring a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer having three component slides, means for moving one of said component slides to positions in accordance with the height of the target, means including a differential for moving the second and third of said slides simultaneously to positions in accordance with the horizontal ranges of the target, a iirst multiplier the inputs of which are settable in accordance with the speed of the target and a selected preparation period of time, motion transmission means connecting the output of the first multiplier to the second and third slide moving means, a second multiplier the inputs of which are settable in accordance with the speed of the target and a computed period of time of iiight of the projectile, motion transmitting means connecting the output of the second multiplier to the differential whereby the third slide is moved independently of the second slide in accordance with changes in horizontal range, ballistic computing means for computing the iiight period and settable in accordance with the position of the iirst slide and in accordance with the position of the third slide including an output moved in proportion to the computed ight period, and motion transmitting means connecting the output of the computing means to the night period input of the second multiplier.

5. Apparatus for use in aiming a gun for ring a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer having two independent rotatable vector arms and three component slides, a shaft for angularly setting one of said arms, a shaft for angularly setting the second of said arms, means for moving said shafts, a first differential the inputs of which are connected to the respective shafts, means for moving one of said slides to positions in accordance with the height of the target, indicating means on 'the height slide overlying the analyzer in position to intersect the vector arms, means including a second diierential for moving the second and third of said slides simultaneously to positions in accordance with the horizontal range of the target, indicating means on the second and third slides overlying the analyzer in position to intersect the vector arms and height indicating means, a first multiplier the inputs of which are settable in accordance with the speed of the target and a selected preparation period of time, motion transmission means connecting Vthe output of the rst multiplier to the second and third slide moving means, a second multiplier the inputs of which are settable in accordance with the speed of the target and a computed period of time of Eight 0f the projectile. motion transmitting means connecting the output of the second multiplier to Athe second diiferential whereby the third slide is moved relative to the second slide in accordance with changes in horizontal range. ballistic computing means for computing the flight period and sett-able in accordance with the movement of the first slide and in accordance with the movement of the third slide including an output moved in proportion to the computed flight period, motion transmitting means connecting the output of the computing means to the flight period input of the second multiplier, a second ballistic computing means for computing the super elevation angle and settable in accordance with the movement of the first slide and in accordance with the movement of the third slide including an output moved in proportion to the super elevation, and a third differential connected to the output of the first differential and the output of the second ballistic computing means whereby the output of the third differential is moved in proportion to the sight angle.

6. Apparatus for use in aiming a gun for liring a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer havingatueeindependent rotatable vector arms and three component slides, a shaft for angularly setting one of said arms, a shaft for angular-ly setting the second of said arms, means for moving the two shafts, a rst differential the inputs of which are connected to the respective shafts, means for moving the first of said Slides to positions in accordance with the height of the target, indicating means on the height slide overlying the analyzer in position to intersect the vector arms, means including a second differential for moving the second and third of said slides simultaneously to positions in accordance with the horizontal ranges of the target, indicating means on the second and third slides overlying the analyzer in position to intersect the vector arms and height indicating means, a rst multiplier the inputs of which are settable in accordance with the speed of the target and a selected preparation period of time, motion transmission means connecting the output of the rst multiplier to the second and third slide moving means, a second multiplier the inputs of which are settable in accordance with the speed of the target and a computed period of time of iiight of the projectile, motion transmitting means connecting the output of the second multiplier to the second differential whereby the third slide is moved relatively to the second slide, ballistic computing means for computing the flight period and settable in accordance with the movement of the first slide and in accordance with the movement of the third slide including an output moved in proportion to the.

computed flight period, motion transmitting means connecting the output of the'computing means to the flight period input of the second multiplier, a second ballistic computing means for computing super elevation angles and settable in accordance with the movement of the first slide and in accordance with the movement of the third slide including an output moved in proportion to the super elevation. a third differential connected to the output of the first differential Aand/theoutputeoLthe second computing means whereby the output of the third differential is moved in proportion to the sight angle, and a dial graduated in deflection units connected to the output of the second ballistic computing means,

7. In apparatus for use in aiming a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector solver having a vector arm and three component slides, means for moving the rst of said slides to positions in accordance with the height of the target, indicating means on the height slide overlying the analyzer in position to intersect the Vector arm, means including a differential for moving the second and third of said slides simultaneously to positions in accordance with the horizontal ranges of the target, indicating means on the second and third slides overlying the analyzer in position to intersect the vector arm and the height indicating means, a nrst multiplier the inputs of which are settable in accordance with the speed of the target and a selected preparation period of time, motion transmission means connecting the output of the first multiplier to the second and third slide moving means, a second multiplier the inputs of which are settable in accordance with the speed of the target and a computed period of time of night of the projectile, motion transmitting means connecting the output of the second multiplier to the differential whereby the third slide is moved relatively to the second slide, ballistic computing means for computing the flight period and settable in accordance with the movement of the first slide and in accordance with the movement of the third slide including an output moved in proportion to the computed flight period, motion transmitting means connecting the output of the computing means to the night period input of the second multiplier, and a dial graduated in fuse setting units connected to the output of the ballistic computing means.

8. Apparatus for use in aiming a gun for firing a projectile at a target approachingJr at a constant height above a horizontal plane, comprising a vector analyzer having a height component slide and tivo horizontal range component slides connected for joint and independent movement, each slide carrying indicating means overlying the analyzer, means to move the height component slide to introduce a height setting in the analyzer, means operative to move the two horizontal range component slides together, means operative to introduce independent movement to one of the latter slides, means settable in accordance with a selected preparation period of time, means settable in accordance with the estimated speed of the target, a first multiplier the inputs of which are connected to the two last mentioned means and the output of which is connected to the means for moving the two horizontal range component slides together, manual operative means also selectively connectable to the last mentioned meansl whereby the slides may be set to an initial position and automatically moved to indicate a horizontal range after the preparation period, a second multiplier with inputs settable in accordance with the speed of the target and a computed flight period and having an output connected to the operative means for introducing independent movement in the one horizontal range component slide, ballistic computing means for computing the flight `period and settableimaccordance with the posi- ,Y

tion of the height component slide and in accordance with the position of the independently movable horizontal component slide and including an output moved in proportion to the computed ight period. and motion transmitting means connecting the output of the computing means to the flight period input of the second multiplier.

RAYMOND E. CROOKE. 

